Asset Quality - Changes in Allowance for Loan and Lease Losses by Loan Category (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 1,626	$ 900	$ 883
Provision	(381)	965	441
Charge-offs	(322)	(522)	(499)
Recoveries	138	79	75
Ending balance	1,061	1,626	900
Total ALLL, including discontinued operations, beginning balance	1,662	910	897
Total provision, including discontinued operations	(387)	960	444
Total charge-offs, including discontinued operations	(326)	(527)	(511)
Total recoveries, including discontinued operations	140	84	80
Total ALLL, including discontinued operations, ending balance	1,089	1,662	910
Provision (credit) for losses on off balance sheet exposures	(37)	56	4
Provision for credit loss, net of tax, related to previously disclosed fraud incident			(139)
Impact of ASC 326 Adoption
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		204
Ending balance			204
Total ALLL, including discontinued operations, beginning balance		235
Total ALLL, including discontinued operations, ending balance			235
Adjusted balance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		1,104
Ending balance			1,104
Total ALLL, including discontinued operations, beginning balance		1,145
Total ALLL, including discontinued operations, ending balance			1,145
Commercial Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	1,099	751	743
Provision	(290)	839	332
Charge-offs	(220)	(405)	(358)
Recoveries	99	38	34
Ending balance	688	1,099	751
Commercial Loans | Impact of ASC 326 Adoption
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		(124)
Ending balance			(124)
Commercial Loans | Adjusted balance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		627
Ending balance			627
Consumer Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	527	149	140
Provision	(91)	126	109
Charge-offs	(102)	(117)	(141)
Recoveries	39	41	41
Ending balance	373	527	149
Consumer Loans | Impact of ASC 326 Adoption
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		328
Ending balance			328
Consumer Loans | Adjusted balance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		477
Ending balance			477
Commercial and industrial | Commercial Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	678	551	532
Provision	(142)	585	311
Charge-offs	(174)	(351)	(319)
Recoveries	83	34	27
Ending balance	445	678	551
Commercial and industrial | Commercial Loans | Impact of ASC 326 Adoption
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		(141)
Ending balance			(141)
Commercial and industrial | Commercial Loans | Adjusted balance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		410
Ending balance			410
Commercial mortgage | Commercial Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	327	143	142
Provision	(114)	184	7
Charge-offs	(40)	(19)	(8)
Recoveries	9	3	2
Ending balance	182	327	143
Commercial mortgage | Commercial Loans | Impact of ASC 326 Adoption
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		16
Ending balance			16
Commercial mortgage | Commercial Loans | Adjusted balance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		159
Ending balance			159
Construction | Commercial Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	47	22	33
Provision	(18)	32	(6)
Charge-offs	0	0	(5)
Recoveries	0	0	0
Ending balance	29	47	22
Construction | Commercial Loans | Impact of ASC 326 Adoption
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		(7)
Ending balance			(7)
Construction | Commercial Loans | Adjusted balance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		15
Ending balance			15
Commercial real estate | Commercial Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	374	165
Provision	(132)	216
Charge-offs	(40)	(19)
Recoveries	9	3
Ending balance	211	374	165
Commercial real estate | Commercial Loans | Impact of ASC 326 Adoption
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		9
Ending balance			9
Commercial real estate | Commercial Loans | Adjusted balance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		174
Ending balance			174
Commercial lease financing | Commercial Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	47	35	36
Provision	(16)	38	20
Charge-offs	(6)	(35)	(26)
Recoveries	7	1	5
Ending balance	32	47	35
Commercial lease financing | Commercial Loans | Impact of ASC 326 Adoption
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		8
Ending balance			8
Commercial lease financing | Commercial Loans | Adjusted balance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		43
Ending balance			43
Real estate — residential mortgage | Consumer Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	102	7	7
Provision	(12)	19	1
Charge-offs	2	(2)	(3)
Recoveries	3	1	2
Ending balance	95	102	7
Real estate — residential mortgage | Consumer Loans | Impact of ASC 326 Adoption
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		77
Ending balance			77
Real estate — residential mortgage | Consumer Loans | Adjusted balance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		84
Ending balance			84
Home equity loans | Consumer Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	171	31	35
Provision	(57)	(3)	7
Charge-offs	(9)	(11)	(19)
Recoveries	5	7	8
Ending balance	110	171	31
Home equity loans | Consumer Loans | Impact of ASC 326 Adoption
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		147
Ending balance			147
Home equity loans | Consumer Loans | Adjusted balance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		178
Ending balance			178
Consumer direct loans | Consumer Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	128	34	30
Provision	(2)	61	38
Charge-offs	(29)	(37)	(41)
Recoveries	8	7	7
Ending balance	105	128	34
Consumer direct loans | Consumer Loans | Impact of ASC 326 Adoption
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		63
Ending balance			63
Consumer direct loans | Consumer Loans | Adjusted balance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		97
Ending balance			97
Credit cards | Consumer Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	87	47	48
Provision	(7)	36	36
Charge-offs	(27)	(39)	(44)
Recoveries	8	8	7
Ending balance	61	87	47
Credit cards | Consumer Loans | Impact of ASC 326 Adoption
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		35
Ending balance			35
Credit cards | Consumer Loans | Adjusted balance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		82
Ending balance			82
Consumer indirect loans | Consumer Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	39	30	20
Provision	(13)	13	27
Charge-offs	(39)	(28)	(34)
Recoveries	15	18	17
Ending balance	2	39	30
Consumer indirect loans | Consumer Loans | Impact of ASC 326 Adoption
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		6
Ending balance			6
Consumer indirect loans | Consumer Loans | Adjusted balance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		36
Ending balance			36
Discontinued Operations
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	36	10	14
Provision	(6)	(5)	3
Charge-offs	(4)	(5)	(12)
Recoveries	2	5	5
Ending balance	$ 28	36	10
Discontinued Operations | Impact of ASC 326 Adoption
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		31
Ending balance			31
Discontinued Operations | Adjusted balance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		$ 41
Ending balance			$ 41